This application relates to fan drive gear systems, and more particularly to assembly of a fan drive gear system having an epicyclic gear train with a rotating carrier that can be incorporated in a gas turbine engine to drive a turbo fan.
Gas turbine engines may employ an epicyclic gear train connected to a turbine section of the engine, which is used to drive the turbo fan through an output shaft. In a typical epicyclic gear train, a sun gear receives rotational input from a turbine shaft through a turbine shaft. A carrier supports intermediate gears that surround and mesh with the sun gear. A ring gear surrounds and meshes with the intermediate gears. In arrangements in which the carrier is fixed against rotation, the intermediate gears are referred to as “star” gears and the ring gear is coupled to the output shaft that drives the turbo fan. In arrangements in which the ring gear is fixed against rotation, the intermediate gears are referred to as “planetary” gears and the carrier is coupled to the output shaft that drives the turbo fan. The output shaft can be supported by a bearing assembly. The bearing assembly and gear train include rotatable components that require lubrication during operation.
The carrier housings are typically split along a central plane, with assembly of the gear train including bringing together and securing the halves of the carrier housing. For improved strength and rigidity, as compared with a two-part housing, it is desirable for an epicyclic gear train to have a unitary carrier housing.